Multimedia conferencing, in which voice, image, data and video are shared among conference call participants, typically is conducted entirely within a packet mode of operation. Audio and extra-audio information is packetized at the end user station and is typically transmitted over a managed Internet Protocol (IP) network. A problem with this approach is that such a conference call is limited to participants with extra-audio capable user stations. Thus, a would-be participant having access only to a standard telephone instrument, referred to herein as a POTS (Plain Old Telephone Service) user, would not be able to participate in the conference in any capacity. Another problem with this approach is that user stations will often broadcast address request messages to determine the appropriate multipoint control unit (MCU). This may present security problems.
In light of these problems, it is desirable to have a multimedia conferencing system that will allow POTS users to participate at a base voice level. It is also desirable to transmit conference master or MCU addresses in a secure manner.